RU2640190C2 - Method for determining change dynamics of erythrocyte sedimentation rate - Google Patents

Abstract

FIELD: medicine.SUBSTANCE: method of determination of the dynamics of erythrocyte sedimentation rate includes mixing studied blood samples with anticoagulant, withdrawing received solution of blood with anticoagulant in a capillary, placing it vertically, while the solution of blood with anticoagulant is spilled with automatic dispenser in hematocrit tube, whose lower end is hermetically clogged, placing the capillary vertically into the slot of centrifuge and carrying out the measurement of the height of layer of plasma free of erythrocytes in rotation mode the centrifuge with angular speed of not more than 50 rpm, then on three pulse dynamic characteristics determining the height of layer of plasma, erythrocyte sedimentation rate, erythrocyte acceleration that are captured in a single time, on which the valid characteristic of erythrocytes sedimentation rate is defined using differential equations.EFFECT: increase in the accuracy of determining the dynamics of the change in the erythrocyte sedimentation rate by several orders.4 dwg, 1 tbl

Description

The invention relates to medicine, namely to laboratory clinical diagnostics, and can be used for laboratory tests, as well as for research purposes.

The value of the erythrocyte sedimentation rate (ESR) is a non-specific indicator widely used in clinical practice to assess the presence of inflammatory processes in the human body in various diseases and allows monitoring the course of the disease and its treatment.

Known accepted in Russia (classical) method for assessing the erythrocyte sedimentation rate, performed according to the Panchenkov method [Laboratory research methods in the clinic / Ed. V.V. Menshikov. - M .: Medicine, 1987. - 368 p.]. A glass graduated tube to a specified level is filled with a mixture of blood with 3.8% sodium citrate (anticoagulant) in a ratio of 4: 1 and placed vertically in a tripod under the clamp (to prevent leakage of blood). One hour after the start of the measurement, the distance (in mm) by which the column of red blood cells has dropped from the initial level is determined by the divisions on the tube

The disadvantage of this method is the long analysis time (more than 1 hour), as well as the difficulties that arise when sampling the volume of capillary blood necessary for the study (at least 0.3 ml) and associated with this fact, violations of the rules for taking and preparing blood for research.

The classic Westergren method is also known [Laboratory research methods in the clinic / Ed. V.V. Menshikov. - M .: Medicine, 1987. - 368 p.]. This is an indicator of the rate of blood separation in a test tube with an added anticoagulant into 2 layers: upper (clear plasma) and lower (settled red blood cells). The erythrocyte sedimentation rate is estimated by the height of the formed plasma layer in mm for 1 hour. The specific gravity of erythrocytes is higher than the specific gravity of the plasma, therefore, in a test tube in the presence of an anticoagulant under the influence of gravity, red blood cells settle to the bottom. The rate at which erythrocyte sedimentation occurs is mainly determined by the degree of their aggregation, i.e. their ability to stick together.

The disadvantage is a violation of the ratio of citrate to blood. When setting the sedimentation reaction, it is important to observe the accuracy of the ratio of citrate and blood (1: 4). More concentrated citrate extracts water from red blood cells and speeds up sedimentation. Less concentrated citrate (hypotonic) causes water to enter the red blood cell and slows down ESR.

The prototype adopted a method for determining the dynamics of changes in the erythrocyte sedimentation rate [see RF patent №2256917, IPC 7 G01N 33/49, publ. July 20, 2005, Bull. No. 13], including mixing the test blood sample with an anticoagulant, sampling the resulting blood solution with an anticoagulant in a capillary, placing it vertically, with subsequent measurement for equal intervals of time the height of the plasma layer free of red blood cells. In this case, the blood solution with the anticoagulant is poured using an automatic dispenser into the hematocrit capillary, the lower end of which is hermetically sealed, the capillary is placed vertically in the centrifuge’s nest and the height of the plasma layer free of red blood cells is measured in the rotation mode of the centrifuge with an angular velocity of not more than 50 r / min at regular intervals during a given time interval, according to the data obtained, determine the maximum value of the erythrocyte sedimentation and build a graph of the dynamics of erythro sedimentation tsitov.

The disadvantage of the prototype is the low accuracy of the measurement due to the determination of the desired values by the statistical calibration characteristic with many measurements.

The technical task is to increase the accuracy of determining the actual characteristics of the erythrocyte sedimentation rate by eliminating the methodological and dynamic measurement error.

This technical problem is solved due to the fact that in the method for determining the dynamics of the erythrocyte sedimentation rate, including mixing the test blood sample with an anticoagulant, sampling the resulting blood solution with an anticoagulant into a capillary, placing it vertically, while the blood solution with anticoagulant is poured using an automatic dispenser in the hematocrit capillary, the lower end, which is hermetically sealed, place the capillary vertically in the centrifuge nest and measure the height of the plasma layer, erythrocyte-free, in a centrifuge rotation mode with an angular speed of not more than 50 rpm, the maximum erythrocyte sedimentation value is determined from the obtained data, unlike the prototype, the dynamics of erythrocyte sedimentation rate is determined by three impulse dynamic characteristics (IDC): IDC of layer height plasma h (t), IDH sedimentation velocity ν (t) of erythrocytes, erythrocyte IDH acceleration g (t), the values of h _1, ν _1, g ₁ which is fixed in a single point in time t ₁ at which are recorded the maximum value of the erythrocyte sedimentation H comrade and the time constant T = -ν / g, and the terminal velocity V, the ratio V = n / T, which determines the actual speed characteristic ν (t) erythrocyte sedimentation

.

.

The essence of the proposed method is illustrated in FIG. 1 ÷ 4. The proposed method includes 2 stages:

Stage 1:

a - measurement of the plasma layer height of the impulse dynamic characteristic;

b - measurement of the sedimentation rate of the impulse dynamic characteristics;

c - measurement of acceleration of erythrocyte sedimentation of impulse dynamic characteristics;

Stage 2:

- registration of informative parameters according to the measured IDH;

- determination by informative parameters of the actual characteristics of the erythrocyte sedimentation rate.

Determining the erythrocyte sedimentation rate includes mixing the test blood sample with an anticoagulant, sampling the resulting blood solution with an anticoagulant in a capillary, and placing it vertically. A blood solution with an anticoagulant is poured using an automatic dispenser into a hematocrit capillary, the lower end of which is hermetically sealed. Place the capillary vertically in the centrifuge’s nest and measure the height of the plasma layer free of red blood cells in the rotation mode of the centrifuge with an angular speed of not more than 50 rpm, according to the data obtained, determine the maximum erythrocyte sedimentation value.

1a. Measure the height of the plasma layer free of red blood cells, at a single point in time t ₁ by the impulse dynamic characteristic.

The experimental dependence h (t) = h of the dynamic process of measuring the height of the plasma layer (Fig. 1, graph 1) varies according to the differential equation

where H is the maximum erythrocyte sedimentation rate,

T is the time constant of the dynamic process.

1b. The erythrocyte sedimentation rate is measured by the impulse dynamic response.

The experimental dependence of the velocity ν (r) = ν of the dynamic process of measuring the height of the plasma layer (Fig. 1, graph 2) is a derivative of the antiderivative (1) corresponding to the second-order differential equation

or taking into account the dependence ν = dh / dt represents a first-order differential equation

1c. The acceleration of erythrocyte sedimentation is measured by impulse dynamic response.

The experimental dependence of the acceleration g (t) = g of the dynamic process of measuring erythrocyte sedimentation (Fig. 1, graph 3) changes as the first derivative of the dynamic process of measuring the rate (2a) of erythrocyte sedimentation according to a second-order differential equation:

or taking into account the dependence g = dν / dt represents a first-order differential equation

2. Register informative parameters according to the measured IDH.

To find the maximum value and the erythrocyte sedimentation time constant at a single instant of time t _1, measure (see Fig. 1) the amplitude h ₁ , velocity ν ₁ and acceleration g ₁ , which record the maximum values: height H of the plasma layer free of red blood cells, erythrocyte velocity V, acceleration of erythrocyte sedimentation G, and the time constant T.

Parameters H and T uniquely determine the dynamic characteristics of the experiment according to dependencies (1), (2), (3), therefore, it is advisable to take them as informative parameters of the dynamic process of sedimentation of red blood cells. The registration of informative parameters H and T is organized according to the measured values of the amplitude h, speed ν, acceleration g at a single moment in time t ₁ .

We express from the obtained equation (2a) an algorithm for registering the parameter T

According to algorithm (4), to register the time constant T, it is necessary to simultaneously measure the velocity ν, acceleration g, and take their ratio.

To find H, we substitute expression (4) into equation (1)

,

,

and taking into account the formulas for determining the velocity ν = dh / dt and acceleration g (t) = g = dν / dt of erythrocyte sedimentation, we transform the differential equation to the algorithm for recording the maximum erythrocyte sedimentation Н

where h ₁ , ν ₁ , g ₁ - respectively, the layer height, speed and acceleration of erythrocyte sedimentation at time t ₁ .

Algorithm (5) shows that for registering the parameter H, it is necessary at time t ₁ to measure the height h _{1 of the} layer, the velocity ν ₁ and the acceleration g ₁ of erythrocyte sedimentation.

As the ratio of the parameters H and V to T, the values of the limiting velocity V are found

and ultimate acceleration

which follow from the limits of the velocity relations ν = dh / dt, as well as the acceleration g = dν / dt.

After registration of the limiting parameters (4-7), the actual characteristics of the layer height h (t) = h, velocity ν (t) = ν and acceleration g (t) = g of erythrocyte sedimentation are restored using formulas (1-3).

The adequacy of the proposed method to the physics of the experiment is proved by mathematical modeling of the investigated (1-3) IDC: the studied h (t) relative to the equivalent (1) of the experimental IDC h _e (t) according to the obtained values (Fig. 1, graphs 1, 4); the investigated IDC ν (t) relative to the equivalent (2) of the experimental IDC ν _e (t) according to the obtained values (Fig. 1, graphs 2, 5); the investigated IDC g (t), relative to the equivalent (3) of the experimental IDC g _e (t), according to the obtained values (Fig. 1, graphs 3, 6).

Assess the adequacy of the obtained dependencies by the formula for determining the relative error

its estimate (8) is presented in FIG. 2.

In this case, the error ε of the deviation of the studied IDCs relative to the experimental ones does not exceed 1.5 * 10 ^-11 .

Similarly, the IDC of speed ν (t) relative to ν _e (t) does not exceed 4 * 10 ^-11 .

The error estimate (8a) is similar to the estimate (8) in FIG. 2.

We will increase the accuracy by taking into account the methodological and dynamic errors by the example of estimating the erythrocyte sedimentation rate ν (t) (2).

1. The methodological error is determined by the nonlinearity η of the velocity ν (t) (2):

The nonlinearity (9) of the prototype regulates the methodological error by the calibration of the characteristic ν (t), approximated by a statistical analysis of many dimensions. In the proposed solution, a methodological error is excluded due to the determination of the limiting velocity V with unit nonlinearity η = 1 (Fig. 3, upper graph) as an informative parameter of the dynamic characteristic ν (t). From formula (9) it follows that the single non-linearity for the prototype is regulated only when ν (t) = V at the initial time t = 0 and tends to zero with increasing time (Fig. 3, lower graph), when the height h (t) the erythrocyte layer tends to the limit H value (see Fig. 1 and 3).

2. The dynamic error δ is also determined through the nonlinearity η

From the expression (10) it can be seen that the dynamic error δ of the prototype grows in proportion to time t (Fig. 4, the upper graph), while the instantaneous value h (t) of the IDC tends asymptotically to the maximum height H (Fig. 1), and IDC ν (t) decreases to 0. For the proposed solution, the dynamic error is excluded and corresponds to the zero level (Fig. 4, lower graph).

Therefore, the proposed method, in contrast to the prototype, eliminates both methodological and dynamic error.

3. Increasing the efficiency of the proposed method evaluates the effectiveness of the measurement time t. In the proposed method, t≤T measurement does not exceed the time constant, and for the prototype 3-5 times greater than t _n = (3-5) T.

для погрешности (5-1)% следует, что оперативность предлагаемого способа в 3-5 раз выше известных способов.From time efficiency

for an error of (5-1)% it follows that the efficiency of the proposed method is 3-5 times higher than the known methods.

The values of errors resulting from the application of the prototype method and the proposed method are shown in the table.

The table shows that the accuracy of the proposed method is ten orders of magnitude higher than the known solution.

Thus, the determination of the dynamics of changes in the erythrocyte sedimentation rate by three impulse dynamic characteristics: IDH of the plasma layer height h (t), IDH of the velocity ν (t) and acceleration g (t) of erythrocyte sedimentation, the values of which are recorded at a single moment in time t ₁ , by which record the maximum value H of erythrocyte sedimentation and the time constant T, as well as the limiting speed V as their ratio, which determine the actual characteristic of the erythrocyte sedimentation rate, in contrast to the known solutions, increases the accuracy s to several orders of magnitude, and the efficiency of not less than 3 times.

Claims (2)

A method for determining the dynamics of a change in the erythrocyte sedimentation rate, which contains mixing a test blood sample with an anticoagulant, collecting the resulting blood solution with an anticoagulant into a capillary, placing it vertically, pouring a blood solution with an anticoagulant using an automatic dispenser into a hematocrit capillary, which is sealed from the lower end, place the capillary vertically in the centrifuge’s nest and measure the height of the plasma layer, which is free of red blood cells, in the centrius rotation mode ugi with an angular speed of not more than 50 rpm, according to the obtained data, the maximum erythrocyte sedimentation value is determined, characterized in that the dynamics of the erythrocyte sedimentation rate is determined by three impulse dynamic characteristics (IDC): IDC of the plasma layer height h (t), IDC of speed erythrocyte sedimentation ν (t), erythrocyte acceleration IDH g (t), the values of h ₁ , ν ₁ , g _{1 of} which are recorded at a single moment in time t ₁ , by which the maximum erythrocyte sedimentation value H and the time constant T = -ν / g are recorded as well as the maximum speed awn V as the ratio V = n / T, which determines the actual speed characteristic ν (t) = ν erythrocyte sedimentation

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